1. Technical Field
The present invention relates to food products. More particularly, the present invention relates to a controlled atmosphere package for produce. In its method aspect, the present invention resides in methods for the refrigerated packaging and storage for extended periods.
2. Prior Art
Present consumer food trends strongly favor increased consumption of fresh food, especially fruits. Consumers are preparing increasing amounts of fruit and fruit salads at home. Restaurants and food service providers are also increasing their offering of fruit based salads in response to consumer desires.
While consumers find at-home fruit salad consumption is desirable from the standpoint of nutrition, taste, etc., at-home salad preparation is time consuming especially for the small portions of salads typically consumed on a daily basis. For added convenience, cut fruit produce blends suitable for quick salad preparation are available from many grocery stores. However, whether prepared at home or purchased from grocery stores, cut produce whether of one type or blends thereof typically have shelf-lives of only a few days to a week. Deterioration of the cut produce is familiar to everyone and is characterized by browning of the cut fruit pieces proximate their cut portions, wilting, color and flavor loss, loss of crisp texture, mold or rot, and the like.
Maintaining the flavor, texture and eating qualities of produce, from time of harvest through the time of purchase and actual consumption has been a problem of long-standing duration. The most common technique for preventing produce from reaching an over-ripe or deteriorated state has been to pick the produce in a relatively unripe state and retard the ripening process by the use of refrigeration. Refrigeration is not without problems. For example, tropical and sub-tropical fruits, e.g., bananas are damaged quickly at refrigerated temperatures. Some fruits become more susceptible to microbial attack.
It would be desirable, of course, to be able to extend the storage life of fresh, ripe cut fruit produce such that the produce could be immediately consumed as well as stored in a ripe state for later consumption. The prior art also includes various packaging and handling techniques for the lengthened storage of whole vegetables and fruits. However, typically whole fruit or vegetable storage shelf life is much greater than cut produce shelf life due to the protective presence of a whole skin or other membranes. The principal mechanism of decay is mold or fungal attack against the protective skin or cover. Accordingly, the teachings with respect to lengthening the storage shelf life of whole fruits and vegetables provides very little practical or valuable guidance for providing packaging for cut fruit produce to extend refrigerated shelf life. Due to the limited shelf life of present cut fruit produce, preparation and sales by grocers is primarily locally based. Extended shelf life of at least four weeks would be needed for production and sale on a regional or national scale which could take advantage of economies of scale in produce source procurement, processing, packaging and the like.
Prior efforts both in the U.S. and elsewhere for providing packaged cut produce with extended shelf life, i.e., more than 7 days, have attempted to manipulate cellular respiration rates because unlike meat or fish, cut fruit produce is still vital. Once cut off from the supply of nutrients, the cells of the produce contain a limited amount of stored energy. Generally, since cell respiration is also strongly influenced by the immediate atmosphere, one or more of three approaches have been taken to manipulate cellular respiration rates through atmosphere control. One approach is to manipulate and control the initial atmosphere sealed into the package. A second approach is to modify the internal package atmosphere by inclusion of either one or more gas absorbents or scavengers or gas releasants. Finally, the third approach is to control the gas permeability of the packaging material so as to control to ingress or egress of biologically significant gases.
U.S. Pat. No. 4,411,921 (issued Oct. 25, 1983 to R. E. Woodruff) is exemplary of modifying the first approach of providing initial atmosphere and discloses incorporation of elevated levels of CO and/or CO.sub.2 with normal or reduced O.sub.2 levels. In U.S. Pat. No. 4,411,918, (issued Oct. 25, 1983 to Cimino et al.) discloses apparatus for preserving food by generating preservative gas. U.S. Pat. No. 4,423,080 (issued Dec. 27, 1983 to Bedrosian et al.) is exemplary of the second approach using gas absorbents and disclose using packets of chemical agents capable of absorbing moisture and carbon dioxide. Also representative of the absorption approach is U.S. Pat. No. 4,337,276 (issued June 29, 1982 to Nakamura et al.) which discloses inclusion of zeolite, bentonate and activated carbon for absorption of released ethylene gas.
Representative of using more than one approach, namely controlling both the package gas permeability and providing a controlled initial atmosphere is U.S. Pat. No. 4,224,347 (issued Sept. 23, 1980 to R. E. Woodruff) which discloses high O.sub.2 and CO initial levels and packaging material of specified gas permeability.
Notwithstanding the long-standing, widespread and intensive efforts of the prior art, the shelf life of refrigerated packaged cut produce blends to date is limited to at best 7 to 10 days. Modest improvements have been made with regard to longer storage of individual types of cut fruit product. However, extension of shelf life of blends of cut fruit produce with widely varying respiration rates, e.g., apples, pineapples and grapes, remains in the art a difficult and unresolved problem. Accordingly, there is a continuing need for improved packaged cut fruit produce blend products of extended refrigerated shelf life and method of produce storage and packaging.